The appeal of smart mobile devices continues to increase with the advances in communication technology. They come in an ever-increasing array of forms, including smart phones, tablet computers with communication capabilities, and watches with communication, navigation and medical testing functions. The major operating systems for smart devices include Apple's iOS, Google-backed Android and Microsoft's Windows Phone. Smart devices are typically characterized by having a substantial number of peripheral devices and a broad range of applications. They are often equipped with GPS systems, blue tooth, WiFi, FM radio, high-resolution cameras and large touchscreens, and support one or more of the various communication modes such as 2G systems including GSM, GPRS and EDGE, and 3G systems including WCDMA, CDMA2000 and TD-SCDMA. Some also support the LTE system. There are thousands of applications that can be downloaded from the web and installed on smart devices, including map navigation, cell phone banking and games.
Various types of sensors can be put into smart devices, including gravity sensors, acceleration sensors, directional sensors, triaxial gyroscopes, distance sensors, light sensors and electronic compasses. A gravity sensor works using piezoelectricity. With the standard application for a gravity sensor, the screen display rotates in sync with the smart device itself when the smart device rotates by about 90 degrees, so that the information shown on the screen, such as text, is maintained in a state that is parallel to gravity, i.e. from top to bottom. An acceleration sensor is an electronic instrument measuring acceleration. A directional sensor detects what direction the device is positioned in, which is not the commonly understood function of a compass. Rather, it can detect whether the device is vertically upright, vertically upside down, horizontally to the left, horizontally to the right, lying face up or lying face down. A directional sensor is more properly called an angular velocity sensor. A triaxial gyroscope detects positions in six different directions, along with mobile tracks and acceleration. A distance sensor uses the principle of time measurement to find distance as a means of detecting the distance of an object. When making a call the screen on the cell phone will automatically turn off, but when the face of the caller moves away from the phone the screen will automatically come back on again and unlock. A light sensor adjusts the brightness of the screen based on the degree of brightness of the light around it. An electronic compass, also known as an azimuth sensor or a digital compass, utilizes the geomagnetic field to establish the North Pole. Smart devices can be equipped with all or a portion of the aforementioned sensors.
Smart devices usually come with a large capacity battery and a large capacity storage unit such as a 4 GB to 32 GB SD card. Large capacity storage units can be internal or external. Internal storage units are installed internally in smart devices as part of their hardware, while external storage devices can be independently extracted and replaced, in which case the smart devices need only provide the capability for reading from and writing to said equipment such as an SD card slot. Costs are obviously higher for smart devices than for cell phones with traditional functions, and they provide stronger processing capabilities, more comprehensive functionality and the ability to store and handle greater amounts of data and information. This also means that losing a smart device is a greater loss to a consumer. The primary loss is the cost of purchasing a new device, though there are also risks associated with the data stored on the storage unit of the lost device. Said risks are characterized by the following: the risk of the disclosure of private information or commercial secrets; and the risk of the destruction of data, such as audio-visual evidence can be deleted by other people resulting from losing the device.
Smart devices generally provide a reset function so that factory settings can be recovered. This operation resets the entire device and deletes all of the data stored on it. Resetting is the equivalent of using a portion of the system stored on the smart device to perform a recovery so that the operating system and all of the data are reset and the cell phone is in a state which is the same or close to how it was when it was shipped from the factory. The reset process uses data stored in the ROM of the smart device. ROM is an abbreviation for “read-only memory.” It is a solid state semiconductor memory unit from which data stored on it beforehand can only be read. Once the information is stored on the ROM it cannot be modified or deleted, and no information on it is lost when the power of the device is turned off. The ROM in smart devices is a little different from the ROM as it is commonly understood. In most circumstances it can only be read and not written upon, though things can be written into the ROM in certain special cases. The ROM in smart devices is where the operating system is stored, and rewriting on it is generally not permitted for the sake of the safety of the system. This is why the operating system stored in the ROM can only be read and not modified or rewritten. However, there are computer programs that can be used to modify and rewrite in the ROM in order to perform system upgrades. What is known as “wiping” is really rewriting in the ROM. System upgrades can be performed by downloading upgrade packages onto the cell phone's storage unit, and then during the reboot process the check and validation are performed after which the mobile device performs the installation, which is when the information in the ROM is updated. Packages used in the ROM of the mobile device to wipe the system or upgrade including the system update package, system upgrade package, and system migration package are known as the ROM installation package.
Using the Android system as an example, a complete root directory for the ROM comprises the following folders and files: four folders including “data,” “META-IN,” “system” and “boot.img.” The data directory contains the programs for installing user applications. The META-IN directory contains information related to the system, generally including information related to the system version of the ROM after being modified. The system directory contains information relating to the system, and is the equivalent of the Windows folder for the Windows operating system. Boot.img is a mirror image file, and is a kernel, which is generally used when migrating the ROM.
Operating systems for mobile devices provide a lock screen function to prevent losses caused by losing a cell phone. Users can specify images and passwords that are required to unlock the screens so that it is difficult for other people to unlock them and use their mobile devices. This is a preliminary form of protection for the data stored on the internal storage unit of the mobile device, but naturally it cannot defend against cracking the locked screen by wiping the device. Privacy protection and anti-theft applications can be installed on mobile devices in the form of cell phone guard software. With these types of software users can set up passwords with respect to the running authority of designated data and applications. They also feature functions such as sending a text message to a designated number when a new card is installed in a phone; when said text message is received, performing specific operations including, for example, a positioning application will proceed, and location information will be sent to a designated number, or a photograph will be taken and said photograph will be sent to a designated number, or a warning sound will be emitted when data on the phone is destroyed, etc.
Numerous anti-theft and security applications for cell phones have appeared in recent years. These include storing the identity information on the SIM (subscriber identity module) card in the ROM of the phone, binding the SIM card to the device, and using the security password set up by the user to check whether the actual owner of the mobile device is the person who is using the phone. This is to determine whether to go into anti-theft mode. The phone's functions are limited when in anti-theft mode, and in some cases certain remote control operations can be performed using the mobile device via the phone number of a predetermined contact. Other applications bind the encryption of the memory card to the identity of the SIM card so that information stored in the memory can only be read when the device owner's SIM card is being used. Other applications check the upgrade package for a cell phone using public and private keys to prevent illegitimate programs from being installed on it.
However, these solutions do not completely resolve issues associated with security and user-friendliness because the user's SIM card is usually lost at the same time as the mobile device. Binding the SIM card to the mobile device will not guarantee that the data stored in the internal memory of the mobile device will not be read, and will not prevent the stored data from being reset if the mobile device is wiped. Furthermore, the mobile device cannot be updated if the SIM card is destroyed.